The pupa is the stage in a butterfly's (or moth's) life when it is encased in a chrysalis and undergoing metamorphosis. It does not eat during this stage.

The pupa stage lasts from a few days to many months (some butterflies overwinter in the pupa stage, and the adult emerges in the spring).

BUTTERFLIESThe pupa of a butterfly is called a chrysalis (derived from the Greek word for gold). The chrysalis of many butterflies (like the Nymphalidae and Satyridae families) are suspended from a silk pad and abdominal hooks. Others (like like swallowtails and sulphurs) also have a silk girdle supporting their mid-section. About a day before the adult butterfly emerges, the chrysalis of many species (including the monarch) becomes transparent.

MOTHS
Some moths spin a silk cocoon which protects the pupa. Some moth larva tunnel into the ground up to several inches where it will pupate.

A cremaster is a support hook (or a cluster of small hooks) at the abdominal (hind) end of a pupa.